Believe it or not, reprogramming is nothing new. In the 1980s, most likely you worked on GM vehicles and changed a MemCal/PROM or two. The purpose of the MemCal PROM then and reprogramming today is to update the Engine Control Module (ECM) with the most current information. Since we are concerned with today’s software reprogramming issues, we will discuss the generic J2534 unit and how and why to use it. So let’s get started.
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What is J2534?
J2534 is the regulated standard for installing software in onboard light duty vehicle computers. It sometimes goes by different names like ECU reprogramming, flash programming, Pass-Thru programming, calibration updating and software updates. J2534 was created for aftermarket shops as a means to repair vehicle emissions systems without purchasing the OE scan tools.
Pass-Thru reprogramming dumps software downloaded (or CD, old style) to a laptop from the OEM service site on the Internet to the J2534 tool. The J2534 tool is then connected to the vehicle Diagnostic Link Connector (DLC) and the data is transferred to the ECM.
Some OEs, including GM, BMW, Jaguar, Toyota, Volvo and VW, use the J2534 interface not only for reprogramming but provide full factory scan tool functions through the device as well. As with any software and hardware configuration, you have to make sure that your laptop meets the requirements for the OE that you are working on. If an aftermarket shop wants to get into the reprogramming business, they will need to have (at a minimum) a laptop or PC (Windows-based operating system), a solid high speed Internet connection, a J2534 tool that is proven compatible with the make you intend to reprogram, a subscription to the OE service website (or purchase access, usually on a one- to three-day basis) and the vehicle that needs the update.
Remember that not all OEs use the same requirements for software or hardware. Make sure you read their requirements before purchasing anything. A good rule of thumb is to purchase a laptop with Windows 7 Professional using an Intel processor (not a Celeron) with at least 4 GB of RAM, 32 BIT (some require 64 BIT) minimum 2 USB, and wireless connection. The laptop will need Windows Internet Explorer, Acrobat Reader and Java with NO virus protection. Next you will need access to the OE information. You can find a complete listing of all the OE service sites at www.NASTF.org. Once you’re on that web page, select the OE websites tab that is on the left of the page and read the information on programming.
Your next step would be to log in and provide all your information, including a password so you can continue to the page where you will select the programming information or scan tool access. After that is completed you are able to download the updated data from the OE website to the laptop. Make sure you your laptop meets the hardware and software requirements for the manufacturer. Connecting your J2534 tool to the vehicle DLC follows this. Software tools such as Drew Techs Tool Box make sure that the J2534 box has the correct firmware and software installed. The Tool Box application also checks the laptop connection to the J2534 box and vehicle along with the ability to check DTCs and provide helpful information and videos. This application takes the guess work out of proper connection of the device and device to vehicle.
One of the easiest OEs to learn on is GM, so let’s use that as our example. From the GM website, we selected Service and Reprogramming Information from the list. The next step is making sure you select TIS2 Web Service Programming for J2534, filling out the form, paying a fee, than downloading the program that will be installed into the vehicle’s computer(s).
Make sure that the following are all in order before you begin: laptop is plugged into a power source, all the connections to the DLC are tight, the J2534 box is attached to the laptop and a very important step is making sure a battery maintainer such as the Fronius, Assocoated or Midtronics GR8 is connected to the vehicle. All of these special chargers maintain battery voltage with very low AC voltage output that is important in order to prevent any problems during the process. Do not reprogram any vehicle without using one of these maintainers. Do not use a battery pack, because it will not maintain the proper battery voltage. Do not use a conventional battery charger, as the AC ripple normally present could cause the programming session to crash. Make sure that all vehicle accessories are turned off and that there are no interruptions during the procedure. Make sure that doors are not opened during the process and if needed, make sure that the recommended fuse (some Toyota vehicles) is removed so other modules will not be affected. Make sure to read all of the information from the OE website along with everything in the Drew Tech Tool Box related to reprogramming of the vehicle.
A 2012 GMC Yukon 5.3L with an illuminated MIL came in with an idle problem along with a P2135 (Throttle Position Correlation) DTC. If you follow the GM recommended procedure for the DTC, you will be instructed to check voltages that in this case were all within specification. Following its chart will lead you to replacing the throttle body only to find out you still have the same problem.
We had a few other GM vehicles from other shops that had already replaced the throttle body with new GM units only to have the same problem. In cases where the throttle body is defective and needs to be replaced, the unit must be relearned following the procedure on the scan tool. But you’re not done there. You will need the capability to reprogram the vehicle in order to complete the repair and prevent the P2135 from coming back. The fix on this vehicle was just to reprogram the vehicle without changing the throttle body. It’s not always replacement of parts that fixes the vehicle.
A 2012 Nissan Altima came in from another shop with a P0101 (Mass Air Flow Sensor) that to some might be a simple diagnosis. If you are thinking that the MAF sensor needs cleaning or replacing you would be dead wrong and the vehicle would still have the same problem. Selecting any Generic/Global scan tool along with the proper service information would be the right place to start. In fact, doing the research was what led to the proper diagnosis. The shop that sent us the vehicle looked the correct information up in Identifix while we confirmed it with ALLDATA.
The fix for this vehicle was not a cleaning or replacement of the MAF, but rather a reprograming of the PCM. Reading the Technical Service Bulletin (TSB) provide us will all the information we needed. Next I connected my Drew Tech CarDaq J2534 device to the vehicle along with using the Nissan NERS (Nissan ECU reprograming software) and purchased the update software. Within an hour the vehicle was fixed without replacing any parts.